Will hydrangeas survive an outdoor reception?

You could use silk flowers, or you can put them in a vitamin B solution made for plants, to help them last longer! Also, you could cover the tables. I'm not sure what your venue has for shade, but that could work as well!

We did hydrangeas for bridesmaid bouquets in the 85 degree FL heat. By the time the reception rolled around, they weren't looking so good. But they were also not in water the whole time, so that could be why. They are known to not hold up well in hot weather. I think for centerpieces in water though, they should be okay.

Hydrangeas are realt fickle and die very easily. I also suggest silk especially since silk hydrangeas are usually better quality than lots of other silk flowers

Hydrangeas, from my understanding are the drama queen of flowers

Definitely use silk hydrangeas. They will be prettier. I think they will die.